Recently telecommunication networks, e.g. mobile communication networks have started to adopt Internet Protocol (IP) based implementations. A typical network element comprises multiple application CPU nodes. Typically one external IP address is used for these CPU nodes, thus resulting in flexible scaling capacity expansion, easy balancing of computing power of each CPU node, and less manual configuration of applications.
However, since one external IP address is used for all the application CPU nodes, the functionality of a load balancer needs to be implemented. Because the topology and internal IP addresses of the CPU nodes are hidden from outside, a load balancer is needed to direct control plane traffic, such as signaling, to the nodes for processing.
Since load balancing is directly dependent on protocols and interfaces involved, and since protocols and interfaces vary depending on network element involved, load balancing typically needs to be implemented on a network element specific basis for it be effective.
General Packet Radio Service (GPRS) is a packet data service designed to support especially digital mobile networks based on the GSM (Global System, for Mobile Communications) standard, UMTS (Universal Mobile Telecommunications System) or GERAN (GSM EDGE Radio Access Network) systems, as well as American Time Division Multiple Access (TDMA) system, the IS-136. Additionally, GPRS may also be connected to an IP Multimedia Subsystem (IMS).
A GPRS enabled mobile communication network comprises a Serving GPRS Support Node (SGSN) and a Gateway GPRS Support Node (GGSN). An SGSN typically delivers packets to GPRS enabled mobile stations (MS) within its service area. A GGSN is typically used as an interface to external IP networks such as the Internet, other mobile service providers' GPRS services, or enterprise intranets. A GGSN may maintain routing information necessary to tunnel the protocol data units (PDU) to the SGSN that services a particular MS.
FIG. 1 discloses an example of a prior art GPRS enabled communication network. The network comprises a Circuit Switched Core Network (CS CN) domain and a Packet Switched Core Network (PS CN) domain. The Packet Switched Core Network domain further comprises an SGSN and a GGSN. A Home Subscriber Server (HSS) connects the SGSN and the Circuit Switched Core Network to each other. The network further comprises IP Multimedia Subsystems connected to the GGSN and the Home Subscriber Server. The network further comprises Radio Access Networks (RAN) connected to the Circuit Switched Core Network and the Packet Switched Core Network.
A GGSN utilizes several interfaces with several protocols. Thus several types of traffic may arrive to a GGSN simultaneously. Typically the traffic associated with a GGSN needs to be delivered to a specific subscriber or to a session on a specific signaling node.
Thus load balancing for a GGSN comprising multiple CPU nodes assigned to a common external IP address needs to address several issues. The load of each application CPU node needs to be balanced. Further, the response message from a source network element needs to be forwarded to a destination application CPU node that previously sent a signaling request to the source network element. Further, a series of sequential signaling messages for information updating and maintaining sent by other network elements to a specific subscriber or session needs to be forwarded to the destination application CPU node serving the particular subscriber or session.
Thus there is need for a solution solving all these issues. Prior art load balancers may solve some of these issues. However, there is no available method providing a solution for all the issues mentioned for a GGSN comprising multiple CPU nodes assigned to a common external IP address.